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COMMUNICATIONS TO 'THE
A d . Calcd. for CUHl806: C, 59.49; H, 7.49. Found: C, 58.97, 59.80; H, 7.73, 7.84. The acid was optically inactive and gave no methoxyl by Zeisel determination. It was soluble in alkali but precipitated on addition of carbon dioxide ; neutral equivalent, 246-268. Titration of a purer sample with a Beckmann pH meter indicated a pKa f f 10 * 0.5 and a neutral equivalent of 230 = a. It gave no color with ferric chloride, sublimed unchanged and was recovered unchanged after boiling for one hour with alcoholic alkali, after refluxing with pyridine-acetic anhydride and after treatment with semicarbazide acetate for two days. The ultraviolet absorption a t 2220 A. had log E = 2.38, decreasing steadily with increasing wave length. In alkaline solution the curve was shifted 350 A. toward the visible, with a maximum between 2350-2450 A.; log e = 2.74. Work designed to elaborate the structure of this compound is in progress. The crude cholesterol fractions contained a different neutral hapten, not yet isolated in pure form, but active in dilutions of 1:100,000. Perhaps these two substances are reponsible for two of the Rh subgroups.
EDITOK
Vol. 70
TABLEI DIPOLEMOMENTDATA FOR SOME ISOMERIC DICHLOROPROPBNES AT 30" Pm(cc.)@
Isomer
#(Debye units)
1,2-Dichloropropene (76" isomer) 43.4 0.84 1,Z-Dichloropropene (93" isomer) 123.0 2.20 1,3-Dichloropropene (alpha or 104" isomer) 9 9 . 5 1 . 9 2 1.78* 1.77" 1,3-Dichloropropene (beta or 112' isomer) 8 6 . 0 1.73 1.81* 1.66' a Determined by the method of Rogers and Roberts, ibid., 68, 844 (1946). Benzene was used as solvent. From vapor phase data by Oriani and Smyth, J. Chem. Phys., 16, 930 (1948). From the "Data Sheet" on 1,3dichloropropenes published by Shell Chemical Corporation, dated 8/4/47.
arises from resonating structures involving the methyl group.4 The dipole moments for the 1,3-dichloropropenes, as listed in the table, are somewhat conflicting. I t would appear that the moment of the cis compound could not be less than that of the trans form. Thus our data as well as that of the Shell Company support the assignment of the CHARLES C. PRICE DAVID H. READ' cis configuration to the alpha or low-boiling isoTHOMAS J. BARDOS~mer, while the data of Smyth gives so little differCHIADAOCHEN ence in the isomers that little choice is possible.
OF CHEMISTRY DEPARTMENT UNIVERSITYOF NOTRE DAME NOTRE DAME,INDIANA RECEIVED AUGUST16, 1948
(4)
(4) Eli Lilly and Company Fellows 1946-1948.
THE CONFIGURATION OF ISOMERIC 1,Z1,3-DICHLOROPROPENES
AND
Cf.Rogers, THISJOURNAL, 69, 1243 (1947).
CHEMICAL LABORATORIES CNIVERSITY OF TENNESSEE HILTONA. SMITH KNOXVILLE, TENNESSEE W. HOLMES KING RECEIVED SEPTEMBER 9, 1948
Sir : Some question has recently arisen concerning the configuration of the isomeric 1,2- and 1,3dichloropropenes. Huntress and Sanchez-Nieva' report the preparation of the lower-boiling isomer of the 1,2-compound (76" isomer) and state that the configuration of the two stereoisomers is still undetermined. (The other isomer boils a t 9 3 O . ) In the case of the 1,3-dichloropropenes, the alpha or low-boiling isomer was assigned the trans configuration by Hatch and Roberts2 due to the fact that, in the presence of cuprous chloride, it was more slowly hydrolyzed than was the beta or highboiling isomer. Andrews and Kepner3questioned this choice, and indicated that no definite assignment could be made on the basis of available experimental evidence. We wish to report results dealing with the dipole moments of these materials. The pertinent data is given in Table I. The dipole moments of the 1,2-compounds seem to indicate beyond any possible doubt that the 76' isomer is the trans form. The small dipole moment which it does have apparently (1) Huntre- and Sanchez-Nieva, THISJOURNAL, TO, 2813 (1948). (2) Hatch and Roberts, ibid., 68, 1196 (1946). 13) Andreas and Kepner. ibid.. 69, 2230 (1947)
EXCHANGE AT THE 6-POSITION OF GCHOLESTERYL METHYL ETHER
Sir : We have recently1 suggested that the predominant mechanism which operates for the conversion of cholesteryl p-toluenesulfonate to the i-ether involves ionization to an intermediate ion I which has the cationic charge distributed be2,+
..;;/J 6 ' 4
+
6
L__
1
tween positions 3 and 6 and which reacts more rapidly with methanol a t position 6 than 3. Postulating the same ion I as an intermediate in the well-known2 rearrangement of an i-compound t o a normal one, one would expect, in the acid-catalyzed conversion of i-methyl to n-ethyl ether, prior formation, to a large extent, of the i-ethyl ether. This we have now been able to confirm. (1) Winstein and Adams, THISJOURNAL, TO, 838 (1048) 02) McKennis. ibid., 69, 2565 (1947)
NEW BOOKS
Oct., 1948
Thus, in a typical experiment, 2.00 g. of icholesteryl methyl ether, m. p. 79.0-79.5’, was subjected to a one-half hour reflux period in absolute ethanol to which was added ethanolic $toluenesulfonic acid (total volume of final solution 37 ml.) 0.001 M in excess of the slight potassium acetate impurity present in the i-methyl ether as usually ~ r e p a r e d . ~The acid was neutralized, the solvent was evaporated, and the organic material was taken up in hexane. Systematic separation of the products by chromatography with the aid of alumina gave rise to 1.09 g. of i-ethyl ether, m. I>. 45.045.5O (reported4 47’), mixed m. p. with authentic material, 45.5-46.0’, [a]2 5 (chloroform) +4’7.10° (1 dcm., c = 2.65) (reported4 [ c Y ] ~ ~ +49.78’ D (c = 1.607)), 0.18 g. of i-methyl ether, m. p. 78.3-’79.5O and 0.48 g. of n-ethyl ether, m. p. 88.0-89.0’. Thus, under these conditions, the ethyl ether product was GS% i-ethyl. The latter ether is converted to n-ethyl a t a very appreciable rate, but the results (3) Stoll, Z. physrol Chcm., 207, 147 (1932). (4) Beynon, Hsilbron and Spring, J . Chem. Soc , 907 (1936)
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serve to indicate the initial conversion of i-methyl ether predominantly to i-ethyl. The i-ethyl ether product was indistinguishable in melting point and optical rotation from authentic i-ethyl ether and has, therefore, the same configuration as that of the product of the first reaction of ion I with ethanol under the usual conditions of preparation of i-ethyl ether. As far as we are aware this represents the first demonstration of exchange a t the 6-position of i-compounds and suggests that, with care, it can be general. The present work strengthens the case for an ~ intermediate ion I in certain forward and reverse i-sterol rearrangements. It supplies evidence neither for nor against some contribution of bimolecular type mechanisms, and these remain possibilities for some rearrangements. DEPARTMENT O F CHEMISTRY UNIVERSITY OF CALIFORNIA S. WINSTEIN Los ANGELES24, CALIFORNIA A. H. SCHLESINGER~ RECEIVED AUGUST30. 1948 (5) National Institute of Health Postdoctoral Fellow, 1947-1948.
NEW BOOKS --_ Biochemistry. Part I. FIAT Review of German Science, 1939-1946. Senior Author, RICHARD KUHN, KaiserWilhelm-Institut fiir Medizinische Forschung, Heidelberg; Co-authors, H. FISCHER, H.-J. BIELIG, H . VON DOBENECK, I). JERCHEL, W. SIEDEL, M . STRELL, K. THOMAS, 0. WARBURC AND G . WEITZEL, Published by Offices of Military Government for Germany, Field Information Agencies Technical, British, French, U. s. Printed under supervision of Dieterich’sche Verlagsbuchhandlung, Inhaber W. Klemm, Wiesbaden, Germany, 1947. 218 pp. Illustrated. 15 X 22.5 cm. This volume, the first of a series of four devoted to biochemistry, consists of six review articles, respectively entitled: “Fat and Fat Metabolism,” by K. Thomas and G. Weitzel (51 pp.); “Invert Soaps and Tetrazolium Salts,” by D. Jerchel (7 pp.) ; “Natural Pigments I,” by H . J. Bielig (42 pp.) ; “Natural Pigments 11, Syntheses of Pyrroles and Bile Pigments,” by H . Fischer and W. Siedel (19 pp.) ; “Natural Pigments 111, Syntheses of Porphyrins, Pentdyopent,” by H. Fischer and H. v. Dobeneck (18 pp.) ; ”‘NaturalPigments LV, Chlorophyll,” by H. Fischer and M . Strell (11 pp.). In addition, the book contains three original articles on carboxyhemoglobin and on the photochemical assimilation of carbon dioxide, by 0. U’arburg. Much of the research work carried out during the war years was inevitably of a highly technical and utilitarian character, and in most instances the individual reports demand detailed study only by specialists. These review articles accordingly constitute a useful readers’ guide for biochemists t o whom the journals published in Germany in 1939 t o 1946 ore only now becoming available. There are, however, several discussions of subjects of general interest. The section on fats and fat metabolism contains a stimulating account of fundamental work by
Treibs (1942-1946) on the chemical reactions involved in the autoxidation of unsaturated fats, which must be carefully considered both by biochemists and by organic chemists. The same applies t o the accounts of methods for the production of fatty acids from hydrocarbons and the studies of the metabolism and nutritional value of glycerides of these acids. The first section on natural pigments includes reviews, of more than ephemeral interest, of developments in the fields of carotenoids, flavines, pyrones and quinones. Of outstanding excellence are the reasoned discussions, by the late Hans Fischer and his associates, of the chemistry of porphyrins and other pigments related t o pyrrole. The sections devoted t o these topics resemble, in scope, articles in our own Chemical Reviews, and may well take a place in the permanent literature on the subject. HAHST. CLARKE
Electrochemical Analysis with Graded Cathode Potential Control. By HARVEYDIEHL, Ph.D., Professor of Chemistry, Iowa State College, Ames, Iowa. Published by The G. Frederick Smith Chemical Co., 867 McKinley Ave., Columbus, Ohio, 1948. vii 56 pp. 15 X 23 cm. Price, bound copies, $1.00 each; paper back copies free on request. Professor Diehl most appropriately has dedicated this booklet t o the late Henry J. S. Sand, who, forty years ago, introduced the technique of controlling the cathode potential in electrolytic separations and electrogravimetric determination of metals. In spite of its obvious advantages the controlled potential method did not become generally popular because of the tedium associated with the manual control of the potential. Recently, however, potentiostats which automatically perform this
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